Elevator control system



E. M. BOUTON ET AL ELEVATOR CONTROL'SYSTEM Filed Oct. 20 1921 INVENTORS Ed arM.Bau1on d? E. Lewis.

ATTORNEY Patented Oct. 27, 1931 EDGAR M. nou'ron, or EAST PITTSBURGH,

PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC COMPANY, A. CORPORATION OF PENNSYLVANIA r OFFICE AND FRANK E. LEWIS, 01' WILKINSIBURG,

ELEVATOR conTnoL SYSTEM Application filed October 20,1921. Serial No. 509,059.

Our invention relates to systems of control and it has particular relation to systems used in connection with elevators, hoists and the like.

It is an object of our invention to provide means whereb an elevator car may be stopped substantia ly level with a desired landing, regardless of the skill of the operator.

It is, another object of our in yention to provide an elevator system wherein the hatchway doors ma be opened while the car is approaching t e floor at a slow speed.

It is a further object of ourinvention to provide an elevator system wherein the normal interlocking feature, which prevents operation of the car while the hatchway doors are open, may be rendered ineffective when the car is'within a predetermined zone in advance of a floor at which a stop is to be made, butin which the interlocking feature is restored when the car is brought to a stop.

Many systems of control have been employed, particularl in connection with fully automatic or pushutton operated elevators, with results that are satisfactory for elevators operating normally at medium speed, say

200 feet per minute. he varying load conditions met in elevator service account for unsatisfactory results in systems of control operating at abnormally hi h car speeds. To render stopping substantial y independent of load conditions, it is found desirable to first reduce the car speed to a very low value before cutting off the power. Among the systems that haveibeen used for attaining abnormally slow-speed operation of elevator motors are those employing shunt-field control, series and shunt armature resistors and multivoltage sources of supply.

We propose to employ a source of variablevoltage supply, commonly known as a Ward Leonard system, together with a shuntwound elevator motor. Such systems have heretofore been used for mine hoisting in which the conditions of service are somewhat tor service.

different from those met in passenger-eleva- We propose to provide a switch in the elevator car for regulating the field current which is applied to the enerator. This switch also controls the 'rection of current through the generator field winding, whereby the direction and speed of the hoistin motor are controlled. An auxiliary swltch mechanism is mounted on t 'e car for assuming control of the hoisting motor, independently of the car switch, when the car switch is in its inoperative position. The auxiliary switching mechanism is actuated by a cam at each floor. It is assumed that the operator will first reduce the car speed in the usual manner and attempt to make an approximate landing.

It is desirable to reduce the car speed on approaching the desired landing by returning the car switch to the off position. The auxiliary switching mechanism is then released and is actuated by a cam in the hatchwey to maintain the power connections and to continuethe movement of the elevator toward the desired landing, at greatly reduced speed- When the desired level is attained, the cam effects interruption of the control circuits to interrupt the power supply and apply the electromechanical brake. In case the carap- AND IANUFACTUBIN G proaches a landing at high speed and it is impossible to eifect alanding without reversing the motor, it is only necessary for the operator to actuate the car switch momentarily in the reverse direction, after which the movement of the car is automatically under control of the auxiliary switching mechanism, as previously indicated.

The single figure of the drawing is a diagrammatic representation of circuits and apparatus embodying our invention.

"A driving motor 1 of a motor-generator set receives current from an auxlliary source of supply through conductors 2 and 3. A generator armature 4' is mechanically connected to the armature of the driving motor 1. A shunt type field winding 5 of the generator is controlled by means of reversing contactors 6 and 7. A hoisting motor 8 is preferably of the shunt type having a field winding 9 connected to the auxiliary .conductors 2 and 3. The elevator machine shown is of the traction'type provided with a driving sheave wheel 11 and an eletromagnetic brake 12 of well-known design. A car switch 13, located in the elevator car, includes a generator field rheostat 14. An electro-magnetically-operated switch 15, which is mounted on the car, is provided with roller switch members 16 and 17 for engaging cams 18, 19 and 20 located in the hatchway and respectively adjacent to the several landings. A door switch 22 is'provided at each landing. We have shown three landings; the system is applicable to any number. The usual overtravel limit switches 23 and 24 are connected in circuit with the operating coils of the reversing contactors 6 and 7 and with the coils of auxiliary relays 25 and 26. A relay 27 controls a circuit through the auxiliary fieldresistor 28.

The driving motor 1 is accelerated by means of a hand-starter 29 and, under normal conditions, will operate continuously. Assuming the elevator car to be at the first floor, as shown, the car switch 13, if actuated to its first upward position, establishes a circuit for the coil of contactor 6 extending from line conductor 2, through conductor 31, contact members 32, 33 and 34, conductor 35, limit switch 24, coil 36 of contactor 6, conductors 37 and 38, door switches 22 and conductor 39 to line conductor 3. Contactor- 6, clpses, establishing a circuit through the generator field windingextending from line conductor 2 through conductor 31, contact members 41 and 42, field resistor 43, conductor 44,

back contact of relay 27, conductors 45 and 46, contactor 6, conductor 47, field winding 5, conductors 48 and 49, contactor 6 and conductor 50 to the line conductor 3. The generator 4 now supplies energy to the elevator motor 8 at lowv voltage since the entire resistor 43 is in circuit with the field-magnet winding 5. The closure of contactor 6 establishes a circuit for the coil 51 of the electromagnetic brake 12 extending from line conductor 2, through conductors 52 and 53,- swltch 54 of contactor 6, conductor 55 and brake coil 51 to the conductor 3. The brake is thereupon released and the elevator car is operated at relatively low speed.

Any form of interlock between the up and down-direction switches 6 and 7 may be used, as is usually provided in elevator-control systems to prevent both of these switches closingt at the same time and causing a short circu1 Simultaneously with the excitation of coil 36,a circuit is established for the (5110i relay 25 extending from conductor 2, through conductor 31, contact members 32, 33 and 34,

conductor 35, limit switch 24, coil 56 and donductor 57 to the line conductor 3. Relay 25, which may be termed. the up relay, closes, the purpose of which will appear as described later in connection with the automatic stopping of the elevator.

The elevator car ascends and is accelerated by movement of the car switch 13 to its extreme left-hand position. The resistor .43 is thereby excluded from circuit with the generator field winding 5, providing maximum field excitation for the generator. In the final extreme position, after excluding resistor 43, the'car switch 13 closes contact members 32, 33 and 59.

The auxiliary switch 15 is provided with an electromagnet having a coil 58 the circuit for which extends from line conductor 2, through conductor 31, contact members 32, 33 and 59, coil 58 and conductors 60 and 50 to line conductor 3. The energization of coil 58 maintains switch 15 in its inoperative position in which roller contact members 16 and 17 are disengaged from cam 18.

a As the elevator approaches the floor at which the operator desires to stop, the car switch 13 is returned to its inoperative position, thereby first opening contact members 32, 33 and 59, deenergizing the auxiliary switch magnet 58, then gradually reducingt-hefield excitation'of the generator 4 and reducing the car speed and lastly opening contact members 32, 33 and 34. The disengagement of the contact members 33 and 59 de-energizes coil 58 and releases the switch mechanism 15. At this instant, it may be assumed that roller member '17 is pass ng over'c'am 20 upon which it will now ride during the upward movement .of the car. Accordingly, the switch arm to which the roller 17 is attached remains in its open position. The roller 16 is below the cam and the corresponding switch arm is actuated by a spring 61 to its closed position.

The contact members 63, 68 of the auxiliary switch 15 close a shunt circuit around the car-switch contact members 32, 33, 34 to maintain the circuit to the tip-direction switch 6 and the up relay 25 independent of the car-switch contact members 32, 33 and 34 (which are opened upon centering the car switch 13). Switches 6 and 25 are thus held in until the auxiliary switch 15 is opened by its roller 16 engaging cam 18 when the car arrives level with the floor.

A circuit is establishedfrom line conductor 2 through conductor 52, relay 25, conductor 62, contact members 63 and 64, conductors 65 and 66 and coil 67 to line conductor 3. The relay 27 now closes and a circuit is lay 27 interrupts the circuit of the resistor section 43 of the field rheostat 14. This circuit is also interrupted by the car switch 13, and an inde ndent circuit, including the auxiliary field resistor 28, is completed from line conductor 2 through resistor 28, conductor 69, relay 27, conductor 46, contactor 6, conductor 47, enerator field winding 5, conductors 48 and 49, contactor 6 and conductor '50 to line conductor 3. The field excitation of the generator is now independent of the rheostat 14 and such value is selected as to maintain an abnormally slow 0 rating speed of the hoisting motor 8. hen the roller member 16 engages the cam 20, it is actuated to disengage contact members 63, 64 and 68 when the car is approximately level with the landing. The circuit reviously traced for coil 36 through the switch 15 is interrupted, and contactor 6 opens to de-energize the enerator field-magnet winding 5 and theregy stop the hoisting motor 8 and to de-energize the coil 51 and permit the application of electromagnetic brake 12. As the car nears the floor level at the low speed, the attendant may start to open the door, so that, by the time the car arrives at the floor level, 'the doors will have been opened and the passengers may enter or leavethe car. This feature of permitting the doors to open prior to the final leveling of the car achieves an important saving in time. Heretofore, this practice has been dangerous, since the possibility of the attendants startin the car before closing the doors would ennger passengers who, seeing the door open, attempt to enter the car while it is moving.

Elevator systems are, therefore, usually providedwit-h door switches, rendering the hoistingmotor inoperative while the doors are open.

In our system, the relay '27 is provided with contact members which shunt the 'door switches 22 outof the circuit when the car is operating at the abnormally low speed.

The circuit for this may be traced from line conductor 2 through conductors 52, the contact members of relay 25, conductor 62, contact members 63, 64 of auxiliary switch 15, conductor 35, limit switch 24, coil 36 of relay 6, conductor 37 to junction point 80,

whence the normal circuit leads through level and after he has opened the door,

conductor 38, door switches 22 and conductor 39 to line conductor 3, but, when relay 27 is energized, the circuit is completed from junction point 80 by way of conductor 81, contact members 82 of relay 27 to line conductor 3.

Thus, if the attendant attempts to speed up the car while it is approaching the floor moving the car switch 13 to the left, the resistor 43 is inoperative to speed up the car and, if'the attendant moves the car switch 13 as byv to the extreme position, the energization of magnet 58 opens the auxiliary switch 15 and deenergizes relay 27, breaking the shunt circuit around the door switches. The car will immediately stop and, cannot started until the door is closed.

In this manner, our system achieves a saving of time by allowing the doors to open prior to the stopping of the car and yet provides an arrangement which is equall as safe as systems wherein the opening 0 the doors stops the car.

The operation of the elevator to lower floors corresponds in every way to the upward movement. The car switch is actuated to its extreme right-hand position, thereby energizing the down contactor 7 and the down relay 26 in place of the up relay 25. A circuit for the generator field winding extends from line conductor 2 through conductor 31, contact members 41 and 42, resistor 69, conductor 44, back contact of'relay 27, conductor 45, contactor 7, conductor 48, field winding 5, conductor 47 and contactor 7 to line conductor 3.

The operation of the elevator in other details correspondsto the operation previously described with the exception that, in its downward movement, uponthe de-energization of the coil 58 of cam switch 15, the roller member 17 released to maintain a circuit for the operating coil of contactor 7 extending from line conductor 2 through conductor 52, relay 26, conductor 72, contact members 73 and 74, conductor 75, limit switch 23, conductor 7 6. coil 77, conductor 37 and relay 27 to line conductor 3. Roller member 16 is maintained inoperative during its engagement with the cam 18. The downward movement of the car effects the engagement of roller 17 and cam 18 and the opening of switch member 7 3 to stop. the elevator substantially level with the desired floor.

It is evident that, should the speed of the car he insufficiently reduced by the operator prior to reaching the desired landing, the elevator will be carried beyond the desired level. This may occasionally occur, in which case it is necessary to momentarily reverse the car switch to effect movement in the desired direction, which movement is maintained by either of the corresponding relays 25 and 26 and the switch 15.

The system embodying our invention rovides great flexibility and smoothness o operation of an elevator, and a wide range of speed adjustment with the slowest possible speed desirable to accomplish accurate landings. The system is also very economical in power consumption. especially in comparison control through resistance. complicated than be again with systems employing field and armature n5 We claim as our invention 1. The combination with a hoisting motor and controlling means therefor comprising a car switch, of a self-holding relay for effecting the operation of the motor in one direction only, a self-holding relay for controlling reverse operation of said motor, independently of the car switch, and means controlled by said relays for regulating the motor speed.

2. The combination with an elevator car and a hoisting motor therefor, of a motorgenerator for supplying current to the hoisting motor, a car switch in the car for controlling the generator voltage and the direction of rotation of said hoisting motor, an auxiliary voltage-modifying means, and means for connecting the auxiliary voltage modifying means to reduce said generator voltage independently of the car switch and for bringing said car to any desired level.

3. The combination with an elevator car and a hoisting motor therefor, of a generator, having a shunt-type field winding, for supplying current to the motor,'a separate source of current for energizing the field winding, means for controlling the excitation of said field winding to control the speed and direction of rotation of said motor, and- -car speed and effect,- an accurate landing when said controlling means is inoperative.

5. The combination with an elevator car and a hoisting motor therefor, of a motorgenerator for supplying current to the hoisting motor, a car switch in the car for controlling tlie generator voltage and the direction of rotation of said hoisting motor, an auxiliary resistor, and means for connecting the resistor to reduce said generator voltage independently of the car switch for bringing said car to any desired level and for maintaining a predetermined slow speed during the levelling operation.

- 6. The combination with an elevator car and ahoisting motor therefor, of a generator for supplying current to said motor, ,a main resistor in one circuit of said generator, 31 car switch for controlling said resistor, an auxiliay resistor, and means ,for substituting said auxiliary resistor for said main resistor to produce a relatively low motor speed.

7. The combination with an elevator car and a hoisting motor therefor, of a generator for supplying current to said motor. a main resistor in the field winding circuit of said generator, a car switch for controlling said resistor, an auxiliary resistor, and means for replacing said main resistor by said auxiliary resistor to produce a slow speed of said motor during the levelling operation.

8. The combination with an elevator car and ahoisting motor therefor, of a generator for supplying current to said motor, a main resistor in the field-winding circuit of said generator, a car switch for controlling said resistor, an auxiliary resistor, means including means on the car operable under levelling conditions to substitute said auxiliary resistor for said main resistoreto insure a slow levelling speed of said motor.

9. In a control system for an elevator operable in a hatchway pasta landing, motive means for said elevator, a door for said hatchway at said landing, interlocking means controlled thereby to prevent operation of said car when any of said doors are open, a levelingfdevice for actuating said motive means to cause said elevator to approach said landing at a predetermined landing speed and to stop thereat, means operable upon actuation of said levelling device for rendering said interlocking means ineffective and for permitting said car to approach said landing only at said predetermined speed and operably responsive to the stopping of said elevator for restoring said interlocking means.

10; In a control system for an elevator operable in a hatchway past a landing, motive means for said elevator, control means for controlling the speed and direction of said motive means, a door for said hatchway at said landing, interlocking means controlled thereby to prevent operation of said car when any of said doors are open, a leveling device for actuating said motive means to cause said elevator to approach said landing at a predetermined landing speed and to stop thereat, means operable upon actuation of said leveling device for rendering said interlocking means in'efiective and for permitting said door to be opened and said car to approach said landing, and for preventing said control means from actuating said motive means at any speed above said predetermined speed, and o rably responsive to the stopping of said e evator for restoring said interlocking means.

11. The combination with an elevator car and a hoisting motor therefor, of a source of variable voltage, controlling-means therefor comprising a resistor in the car for regulating the motor-speed. and a switch controlled by movements of said car for rendering said resistor ineffective and for effecting accurate stops.

12. In a control system for an elevator car operable past a floor, up-direction-control means, down-direction-control means, carswitch means for selectively actuating said control means, landing-control means for maintaining the actuated direct-control means active until said car arrives level with said floor, one or more closures associated with said car, closure-interlocking means for preventing operation of said car when any of said closures are open, means operable by said landing-control means for renderin said interlocking means inefiective an means operable by actuation of said selecting means in an attempt to select the other of said direction-control means when any of said closures are open and prior to the arrival of saidcar level with said floor for immediately stopping said car.

13. In a control system for an elevator car i operable past a floor, up-direction-control subscribed our names means, doWn-direction-control means, carswitch means for selectively actuating said control means and for controlling the speed of said car, landing-control means for maintaining the actuated direct-control means active until said car arrives level with said floor and for causing said car to travel only at a predetermined low speed, one or more closures associated with said car, closure-interlocking means for preventing operation of said car when anyof said closures is open, means operable by 'said landing-control means for rendering said interlocking means ineffective and means operable by actuation of said selecting means in an attempt to select the other of said direction-control means or to increase the speed of said car when anyof said closures are open and prior to the arrival of said car level with said floor for immediately stoppin said car.

In testimony whereof, we ave hereunto ber, 1921.

EDGAR M. BOUTON. FRANK E; LEWIS.

this 17th day of Octo- 

